The present invention generally relates to a numerical control apparatus, and more particularly to a machine tool which is controlled to move along a plurality to separate translation axes.
Numerical control apparatus have been widely utilized awith a process control system so as to realize automatic operations and improve machining precision of machine tools.
In such machine tools, a workpiece is fixed on a working table, and this working table is moved or translated along an X-axis and a Y-axis based on data initially input in such a manner that the workpiece is positioned opposite to a tool such as a cutting tool and a drill in these machine tools. After such an initial translation, these tools are translated a predetermined distance toward the workpiece along an X-axis, a Y-axis and a Z-axis perpendicular to the X and Y-axes so as to process the workpiece. These tools are positioned, for example, one on the X-axis for machining the plane of the workpiece normal to the X-axis and the other on the Y-axis machining the plane of the workpiece normal to the Y-axis, and are translated either in incremental translation steps or moved in one step to absolute coordinates. Often it is required to control these tools so that their translation can be performed either in synchronism with or independently of each other. Also, it may be required to translate a tool in a vectorial direction in which the translation consists of multi-axial components and therefore translations along all axes must be in synchronism.
The process data to control the translation of the working table in both the X-axis and Y-axis and to control the translation of the tools in the X-axis, the Y-axis, and the Z-axis is initially stored into numerical control apparatus as numerical data.
In one prior art example of numerical control apparatus for a machine tool, numerical data is broken down into axis data, velocity data, and distance data and these data are stored in separate regions of a memory unit as shown in FIG. 3.
In a memory unit 4, axis data for designating the axis in which a translation is to be performed, velocity data for designating a velocity at which the translation is to be performed in the axis, and the distance across which the translation is to be performed in the axis are each stored in memory regions 41, 42 and 43 respectively.
The translation, in this prior art example, in each axis is successively effected, and tools can be translated in a single axis at a time but not in a vectorial direction defined by plural axes.
In another prior art example, the numerical control apparatus can perform a vectorial translation. Naturally, the translation components in plural axes are performed at the same time, namely in synchronism with each other. But, in this prior art apparatus, it is not possible to simultaneously operate plural tools, each moving in an axis different from axes in which the other tools move.